With the rapidly expanding development of personal computers into the field of first what was termed portable, then lap-top, notebook and now hand held size computers, there has been a tremendous demand for maintaining the performance of the disc drive systems of such small computers. The major development in this direction has been the development of smaller Winchester-type disc drives as replacements and enhancements to floppy disc drives for program and memory storage. The Winchester disc drive, in general, provides higher capacities and faster speeds of operation than floppy disc drives, factors which are of great importance for effective use of personal computers running advanced software packages.
The Winchester-type disc drives that have been developed for the personal computer market were initially based on the use of hard discs of a diameter of approximately 5.25 inches. Many of these disc drives used stepper motors for positioning a transducer over a selected track on the rotating disc, although larger capacity systems typically used voice coil motors. The next step in reducing the size of the disc drive was to cut the "form factor" (the dimensions of the external case for the complete disc drive) by one half, so that the resulting disc drive used a platter of 3.5 inch diameter. And most recently, disc drives having 2.5 inch diameter discs have become a common component of lap-top and notebook computers.
With the coming of notebook and hand held computers, the height of the disc drive was also becoming a significant factor, and efforts were made to reduce the height of the disc drive as well, so that the size of the casing for the computer could be minimized. However, as to most notebook computers, hard disc drives continue to be external devices.
It is a primary objective of the present invention to provide a compact hard disc drive system having reduced length, width and height dimensions that is compatible with notebook and hand held computer applications.
Another objective of the invention is to provide a compact hard disc drive system which may be inserted and removed from the computer, both to maximize the effectiveness of the disc drive and provide additional storage capacity by interchanging disc drives, as well as to provide security for the information stored on the disc drive.
A further objective of the present invention is to provide a disc drive which is compatible with the reduced power budget available in a battery-operated portable computer. Typically, portable computers only provide five volt DC power, which must be capable of providing sufficient power both to maintain the disc spinning at a constant speed, and powering the motor of the head arm actuator to selectively position the head over a track on the disc and maintain the head position over the target track on the disc.
Another object of the present invention is to utilize a voice coil motor design which is extremely compact yet capable of reliable positioning of the transducer supporting actuator arm relative to the disc on a long term basis.
Yet another objective of the invention is to provide quick connect/interconnect capability on the outer portions of the disc drive system to provide a simply-connected interface to the drive control electronics or host computer.
Yet another objective is to provide a small, low cost, but effective, magnetic latch and crash stop arrangement for limiting the motion of the actuator assembly used to position the transducers over the disc.